1017 



Abstract. -The humpback whale 

 tMcgaptera nocaeangliae) is a cosmo- 

 pohtan species whose stocks were dras- 

 tically decreased by conimercia! whal- 

 ing practices prior to 1967. The North 

 Pacific population was estimated to be 

 between 15.000 and 20.000 animals 

 before the practice of whaling. At the 

 time of the commencement of its inter- 

 national protection in 1967, this popu- 

 lation may have been reduced to fewer 

 than 1000 individuals. The Pacific coast 

 of Mexico and the Revillagigedo Archi- 

 pelago constitute one of the main breed- 

 ing and calving areas for North Pacific 

 humpback whales. The objective of this 

 paper is to present an estimation of 

 abundance of humpback whales in this 

 region based on photographic identifi- 

 cation of individual animals. Estimates 

 of population size were obtained by us- 

 ing mark and recapture models for both 

 closed and open populations, with each 

 year representing a capture occasion. 

 A total of 1184 humpback whales were 

 identified in Mexican waters between 

 1986 and 1993. The best estimates of 

 population size for the Mexican stocks 

 were those provided by the modified 

 Jolly-Seber method: 1813 OS^r CI: 918- 

 2505) for the coastal stock in 1992, and 

 914 (95'y CI: 590-1193) for the Revil- 

 lagigedo stock in 1991. 



Population size of humpback whale, 



Megaptera novaeangliae, 



in waters off the Pacific coast of Mexico 



Jorge Urban R. 



Departamento de Biologia Marina 



Universidad Autonoma de Baia California Sur 



Ap Post 19-B 



La Paz, BC-S. 23081 Mexico 



E-mail lurbana'calafia uabcs mx 



Carlos Alvarez F. 



Mario Salinas Z. 



Laboratorio de Mamiferos Marines 

 Universidad Nacional Autonoma de Mexico 

 Ap, Post 70-572 

 Mexico, D F 04510 Mexico 



Jeff Jacobsen 



PO Box 4492 



Areata, California 95521 



Kenneth C. Balcomb III 



Center for Whale Research 

 1359 Smugglers Cove Road 

 Fnday Harbor, Washington 98250 



Armando Jaramillo L. 



Departamento de Biologia Marina 

 Universidad Autonoma de Baia California Sur 

 Ap. Post 19-B 

 La Paz, B.C.S- 23081 Mexico 



Paloma Ladron de Guevara P. 

 Anelio Aguayo L. 



Laboratorio de Mamiferos Marines 

 Universidad Nacional Autonoma de Mexico 

 Ap Post 70-572, Mexico, DP 04510 Mexico 



Manuscript accepted 15 January 1999. 

 Fish. Bull. 97:1017-1024 ( 1999)'. 



Humpback whales, Megaptera no- 

 vaeangliae, make seasonal migra- 

 tions between low-latitude winter- 

 ing areas used for mating and calv- 

 ing and high-latitude feeding areas. 

 The general distribution of feeding 

 areas in the North Pacific covers 

 coastal waters in the western North 

 Pacific from northern Japan 

 throughout the Bering Sea and in 

 the eastern North Pacific as far 



south as southern California. Dur- 

 ing the winter breeding season, 

 these whales congregate in three 

 geographically isolated tropical ar- 

 eas: the Ryukyuan, Bonin, and 

 Mariana Islands south of Japan; the 

 islands of the Hawaiian Archi- 

 pelago: and the Pacific coast of 

 Mexico and the Revillagigedo Archi- 

 pelago (Rice, 1974; Johnson and 

 Wolman, 1984). 



